1. Technical Field
This invention generally relates to electric circuit apparatus and, more particularly, to group operated circuit disconnect apparatus for overhead electric power distribution lines carried on poles.
2. Background Art
Overhead electric power distribution lines are mounted upon poles by a wide variety of mounting structures. The poles may be 40-50 feet high and the mounting means often carry various distribution apparatus. For instance, the distribution lines require circuit disconnect means at certain locations. Since such distribution lines commonly operate in a three-phase system, there are three associated lines which ordinarily must be disconnected and reconnected simultaneously. This requires group operated switches. Support structures also are mounted intermediate or down on the pole for distribution at certain locations to various facilities remote from the main power line.
One problem with prior art group operated circuit disconnect devices is that such apparatus can have rotatable or sliding parts which are exposed to the weather where they may become corroded, or where they may become immobilized in the winter because of ice formed on the parts. Exposed components of a disconnect device cannot be easily insulated and, in addition, are often aesthetically undesirable.
Another problem with existing group operated circuit disconnect devices is that such apparatus typically have a plurality of disconnect switches, each switch having a rotatable switch blade receivable in a single set of jaw contacts for closing a circuit. As a result of the high voltage with which such devices are used, pre-arcing between the switch blade and the jaw contacts during switch closing can cause severe damage to or even destroy the contacts. Particularly, when a switch is closed into a faulted circuit, arcing can render the blade incapable of carrying its full rated load current.
This invention is directed to solving these problems by providing a new and improved group operated switching apparatus including a support structure for mounting the distribution lines on a pole, the structure being efficient and inexpensive to manufacture, yet providing improved performance not heretofore available.